Can anyone advise -
When driving at slow speeds 10 - 20 mph and I apply brakes - I feel and hear grinding sound. On the brake pedal it feels like you are trying to stop a rotating motor. There is also the sound of a pump or motor running which sometimes does not stop after releasing the brakes. This happens more often than not.
When I remove the fuses to the abs pump and control unit this fault does not happen.
I would gratefully appreciate any advice.

Jasboy - james91159@ky11.freeserve.co.uk

If this is happening on a wet,icy or snow covered road it is the abs doing what it was built to do -prevent lockup of any wheel

The grinding sound suggests that the pads are gone and you have a metal to metal situation. This may be causing the ABS to kick in. Significantly worn front suspension components can also cause various braking asscoiated anomalies.

do you have the TRACs/ABS warning light come on at all? If so you may have a bad control module. I experienced a variety of braking anomalies when mine went eg. intermittent ABS activation under normal dry braking conds at slow speeds.


The grinding is very worrisome-pull the wheels and look for severe pad wear and rotor scoring.

Matt

Thanks for reply - however I checked pads and all are fine. Looking at the rear rotor shows that the pads are not contacting completely as the rotor is not completely shiny. I cant see the abs light on dash and only light on is service which goes off after 5 mins.

Since it only happens at slow speeds does this not point to a bad wheel sensor?

I can only assume wheel sensor or abs pump or control unit has gone.

Cheers
Jasboy

Do a search here on "'96 ABS" as '96 can have a specific, known wiring problem regarding front ABS sensor wires located under the fusebox (which must be removed, lifted upwards to gain access). There was an old paper TSB on the subject too.
You need to know what fault codes are stored using a scan tool. If front wheel sensor codes, it needs the wiring repair. If rear wheel sensor or pump motor codes, you need a new ABS control unit. Don't guess w/o knowing the codes stored first. A dealers VST scan tool might be the only scan tool that can read ABS codes? Don't know if aftermarket scan tools can do that.

The 850's also do a low speed self test upon first start. Mine will activate even if I hit a slight bump in the road with no brakes applied. Just a weird system.

I have same prob. Done a diagnostic and it seems to be a combination of a broken abs sensor(rear offside) and a broken load sensor on the back axle.